[PATCH 0/5] Misc driver core changes (constness)

[PATCH 0/5] Misc driver core changes (constness)

[Dmitry Torokhov]

Hi,

It all started when code like this:

static const char driver_name = "blah";
static struct device_driver {
	.name = driver_name,
};

would give me compiler warning about removing constness because driver
core has "name" fields drclared simply as "char *". I think it is a good
idea to have them as "const char *" since whoever accesses them should
not try to change them.

01-hotplug-use-kobject-name.patch
  - kobject_hotplug should use kobject_name() instead of
    accessing kobj->name directly since for objects with
    long names it can contain garbage.

02-sysfs-link-constness.patch
  - make sysfs_{create|remove}_link to take const char * name.

03-kobject-const-name.patch
  - make kobject's name const char * since users should not
    attempt to change it (except by calling kobject_rename).

04-kset-name-const.patch
  - change name() method in kset_hiotplug_ops return const char *
    since users shoudl not try to modify returned data.

05-driver-const-name.patch
  - change driver's, bus's, class's and platform device's names
    to be const char * so one can use const char *drv_name = "asdfg";
    when initializing structures.
    Also kill couple of whitespaces.

Please consider for inclusion.

-- 
Dmitry

[PATCH 1/5] kobject_hotplug() should use kobject_name()

[Dmitry Torokhov]

kobject: kobject_hotplug should use kobject_name() instead of
         accessing kobj->name directly since for objects with
         long names it can contain garbage.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 kobject_uevent.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

Index: dtor/lib/kobject_uevent.c
===================================================================
--- dtor.orig/lib/kobject_uevent.c
+++ dtor/lib/kobject_uevent.c
@@ -246,10 +246,10 @@ void kobject_hotplug(struct kobject *kob
 	if (hotplug_ops->name)
 		name = hotplug_ops->name(kset, kobj);
 	if (name == NULL)
-		name = kset->kobj.name;
+		name = kobject_name(&kset->kobj);
 
 	argv [0] = hotplug_path;
-	argv [1] = name;
+	argv [1] = name;
 	argv [2] = NULL;
 
 	/* minimal command environment */

[PATCH 2/5] sysfs_{create|remove}_link should take const char *

[Dmitry Torokhov]

sysfs: make sysfs_{create|remove}_link to take const char * name.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 fs/sysfs/symlink.c    |    8 ++++----
 include/linux/sysfs.h |   10 +++++-----
 2 files changed, 9 insertions(+), 9 deletions(-)

Index: dtor/include/linux/sysfs.h
===================================================================
--- dtor.orig/include/linux/sysfs.h
+++ dtor/include/linux/sysfs.h
@@ -105,11 +105,11 @@ sysfs_chmod_file(struct kobject *kobj, s
 extern void
 sysfs_remove_file(struct kobject *, const struct attribute *);
 
-extern int 
-sysfs_create_link(struct kobject * kobj, struct kobject * target, char * name);
+extern int
+sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name);
 
 extern void
-sysfs_remove_link(struct kobject *, char * name);
+sysfs_remove_link(struct kobject *, const char * name);
 
 int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr);
 int sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr);
@@ -153,12 +153,12 @@ static inline void sysfs_remove_file(str
 	;
 }
 
-static inline int sysfs_create_link(struct kobject * k, struct kobject * t, char * n)
+static inline int sysfs_create_link(struct kobject * k, struct kobject * t, const char * n)
 {
 	return 0;
 }
 
-static inline void sysfs_remove_link(struct kobject * k, char * name)
+static inline void sysfs_remove_link(struct kobject * k, const char * name)
 {
 	;
 }
Index: dtor/fs/sysfs/symlink.c
===================================================================
--- dtor.orig/fs/sysfs/symlink.c
+++ dtor/fs/sysfs/symlink.c
@@ -43,7 +43,7 @@ static void fill_object_path(struct kobj
 	}
 }
 
-static int sysfs_add_link(struct dentry * parent, char * name, struct kobject * target)
+static int sysfs_add_link(struct dentry * parent, const char * name, struct kobject * target)
 {
 	struct sysfs_dirent * parent_sd = parent->d_fsdata;
 	struct sysfs_symlink * sl;
@@ -79,7 +79,7 @@ exit1:
  *	@target:	object we're pointing to.
  *	@name:		name of the symlink.
  */
-int sysfs_create_link(struct kobject * kobj, struct kobject * target, char * name)
+int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name)
 {
 	struct dentry * dentry = kobj->dentry;
 	int error = 0;
@@ -99,13 +99,13 @@ int sysfs_create_link(struct kobject * k
  *	@name:	name of the symlink to remove.
  */
 
-void sysfs_remove_link(struct kobject * kobj, char * name)
+void sysfs_remove_link(struct kobject * kobj, const char * name)
 {
 	sysfs_hash_and_remove(kobj->dentry,name);
 }
 
 static int sysfs_get_target_path(struct kobject * kobj, struct kobject * target,
-				   char *path)
+				 char *path)
 {
 	char * s;
 	int depth, size;

[PATCH 3/5] Make kobject's name be const char *

[Dmitry Torokhov]

kobject: make kobject's name const char * since users should not
	 attempt to change it (except by calling kobject_rename).

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 include/linux/kobject.h |    6 +++---
 lib/kobject.c           |    2 +-
 lib/kobject_uevent.c    |    4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

Index: dtor/include/linux/kobject.h
===================================================================
--- dtor.orig/include/linux/kobject.h
+++ dtor/include/linux/kobject.h
@@ -33,7 +33,7 @@
 extern u64 hotplug_seqnum;
 
 struct kobject {
-	char			* k_name;
+	const char		* k_name;
 	char			name[KOBJ_NAME_LEN];
 	struct kref		kref;
 	struct list_head	entry;
@@ -46,7 +46,7 @@ struct kobject {
 extern int kobject_set_name(struct kobject *, const char *, ...)
 	__attribute__((format(printf,2,3)));
 
-static inline char * kobject_name(struct kobject * kobj)
+static inline const char * kobject_name(const struct kobject * kobj)
 {
 	return kobj->k_name;
 }
@@ -57,7 +57,7 @@ extern void kobject_cleanup(struct kobje
 extern int kobject_add(struct kobject *);
 extern void kobject_del(struct kobject *);
 
-extern int kobject_rename(struct kobject *, char *new_name);
+extern int kobject_rename(struct kobject *, const char *new_name);
 
 extern int kobject_register(struct kobject *);
 extern void kobject_unregister(struct kobject *);
Index: dtor/lib/kobject.c
===================================================================
--- dtor.orig/lib/kobject.c
+++ dtor/lib/kobject.c
@@ -280,7 +280,7 @@ EXPORT_SYMBOL(kobject_set_name);
  *	@new_name: object's new name
  */
 
-int kobject_rename(struct kobject * kobj, char *new_name)
+int kobject_rename(struct kobject * kobj, const char *new_name)
 {
 	int error = 0;
 
Index: dtor/lib/kobject_uevent.c
===================================================================
--- dtor.orig/lib/kobject_uevent.c
+++ dtor/lib/kobject_uevent.c
@@ -197,7 +197,7 @@ void kobject_hotplug(struct kobject *kob
 	int i = 0;
 	int retval;
 	char *kobj_path = NULL;
-	char *name = NULL;
+	const char *name = NULL;
 	char *action_string;
 	u64 seq;
 	struct kobject *top_kobj = kobj;
@@ -249,7 +249,7 @@ void kobject_hotplug(struct kobject *kob
 		name = kobject_name(&kset->kobj);
 
 	argv [0] = hotplug_path;
-	argv [1] = name;
+	argv [1] = (char *)name; /* won't be changed but 'const' has to go */
 	argv [2] = NULL;
 
 	/* minimal command environment */

[PATCH 4/5] kset_hotplug_ops->name shoudl return const char *

[Dmitry Torokhov]

kobject: change name() method in kset_hotplug_ops return const char *
	 since users shoudl not try to modify returned data.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
 drivers/base/class.c    |    2 +-
 drivers/base/core.c     |    2 +-
 include/linux/kobject.h |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

Index: dtor/drivers/base/class.c
===================================================================
--- dtor.orig/drivers/base/class.c
+++ dtor/drivers/base/class.c
@@ -262,7 +262,7 @@ static int class_hotplug_filter(struct k
 	return 0;
 }
 
-static char *class_hotplug_name(struct kset *kset, struct kobject *kobj)
+static const char *class_hotplug_name(struct kset *kset, struct kobject *kobj)
 {
 	struct class_device *class_dev = to_class_dev(kobj);
 
Index: dtor/include/linux/kobject.h
===================================================================
--- dtor.orig/include/linux/kobject.h
+++ dtor/include/linux/kobject.h
@@ -94,7 +94,7 @@ struct kobj_type {
  */
 struct kset_hotplug_ops {
 	int (*filter)(struct kset *kset, struct kobject *kobj);
-	char *(*name)(struct kset *kset, struct kobject *kobj);
+	const char *(*name)(struct kset *kset, struct kobject *kobj);
 	int (*hotplug)(struct kset *kset, struct kobject *kobj, char **envp,
 			int num_envp, char *buffer, int buffer_size);
 };
Index: dtor/drivers/base/core.c
===================================================================
--- dtor.orig/drivers/base/core.c
+++ dtor/drivers/base/core.c
@@ -105,7 +105,7 @@ static int dev_hotplug_filter(struct kse
 	return 0;
 }
 
-static char *dev_hotplug_name(struct kset *kset, struct kobject *kobj)
+static const char *dev_hotplug_name(struct kset *kset, struct kobject *kobj)
 {
 	struct device *dev = to_dev(kobj);
 

[PATCH 5/5] make driver's name be const char *

[Dmitry Torokhov]

Driver core:
  change driver's, bus's, class's and platform device's names
  to be const char * so one can use
            const char *drv_name = "asdfg";
  when initializing structures.
  Also kill couple of whitespaces.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 drivers/usb/core/devices.c |    2 +-
 include/linux/device.h     |   12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

Index: dtor/include/linux/device.h
===================================================================
--- dtor.orig/include/linux/device.h
+++ dtor/include/linux/device.h
@@ -47,7 +47,7 @@ struct class_device;
 struct class_simple;
 
 struct bus_type {
-	char			* name;
+	const char		* name;
 
 	struct subsystem	subsys;
 	struct kset		drivers;
@@ -98,17 +98,17 @@ extern int bus_create_file(struct bus_ty
 extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
 
 struct device_driver {
-	char			* name;
+	const char		* name;
 	struct bus_type		* bus;
 
 	struct completion	unloaded;
 	struct kobject		kobj;
 	struct list_head	devices;
 
-	struct module 		* owner;
+	struct module		* owner;
 
 	int	(*probe)	(struct device * dev);
-	int 	(*remove)	(struct device * dev);
+	int	(*remove)	(struct device * dev);
 	void	(*shutdown)	(struct device * dev);
 	int	(*suspend)	(struct device * dev, pm_message_t state, u32 level);
 	int	(*resume)	(struct device * dev, u32 level);
@@ -142,7 +142,7 @@ extern void driver_remove_file(struct de
  * device classes
  */
 struct class {
-	char			* name;
+	const char		* name;
 
 	struct subsystem	subsys;
 	struct list_head	children;
@@ -369,7 +369,7 @@ extern struct device *device_find(const 
 /* drivers/base/platform.c */
 
 struct platform_device {
-	char		* name;
+	const char	* name;
 	u32		id;
 	struct device	dev;
 	u32		num_resources;
Index: dtor/drivers/usb/core/devices.c
===================================================================
--- dtor.orig/drivers/usb/core/devices.c
+++ dtor/drivers/usb/core/devices.c
@@ -239,7 +239,7 @@ static char *usb_dump_interface_descript
 	int setno)
 {
 	const struct usb_interface_descriptor *desc = &intfc->altsetting[setno].desc;
-	char *driver_name = "";
+	const char *driver_name = "";
 
 	if (start > end)
 		return start;

Re: [PATCH 0/5] Misc driver core changes (constness)

[Greg KH]

On Tue, Apr 26, 2005 at 02:29:03AM -0500, Dmitry Torokhov wrote:
> Hi,
> 
> It all started when code like this:
> 
> static const char driver_name = "blah";
> static struct device_driver {
> 	.name = driver_name,
> };
> 
> would give me compiler warning about removing constness because driver
> core has "name" fields drclared simply as "char *". I think it is a good
> idea to have them as "const char *" since whoever accesses them should
> not try to change them.
> 
> 01-hotplug-use-kobject-name.patch
>   - kobject_hotplug should use kobject_name() instead of
>     accessing kobj->name directly since for objects with
>     long names it can contain garbage.
> 
> 02-sysfs-link-constness.patch
>   - make sysfs_{create|remove}_link to take const char * name.
> 
> 03-kobject-const-name.patch
>   - make kobject's name const char * since users should not
>     attempt to change it (except by calling kobject_rename).
> 
> 04-kset-name-const.patch
>   - change name() method in kset_hiotplug_ops return const char *
>     since users shoudl not try to modify returned data.
> 
> 05-driver-const-name.patch
>   - change driver's, bus's, class's and platform device's names
>     to be const char * so one can use const char *drv_name = "asdfg";
>     when initializing structures.
>     Also kill couple of whitespaces.
> 
> Please consider for inclusion.

Very nice, I've added all 5 patches to my tree, and are queued up for
after 2.6.12 is out.

thanks,

greg k-h

[PATCH 6/5] Make attributes names const char *

[Dmitry Torokhov]

sysfs: make attributes and attribute_group's names const char *

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 drivers/infiniband/core/sysfs.c |  122 ++++++++++++++++------------------------
 drivers/pci/pci-sysfs.c         |   13 ++--
 include/linux/sysfs.h           |    4 -
 3 files changed, 59 insertions(+), 80 deletions(-)

Index: dtor/include/linux/sysfs.h
===================================================================
--- dtor.orig/include/linux/sysfs.h
+++ dtor/include/linux/sysfs.h
@@ -16,13 +16,13 @@ struct kobject;
 struct module;
 
 struct attribute {
-	char			* name;
+	const char		* name;
 	struct module 		* owner;
 	mode_t			mode;
 };
 
 struct attribute_group {
-	char			* name;
+	const char		* name;
 	struct attribute	** attrs;
 };
 
Index: dtor/drivers/pci/pci-sysfs.c
===================================================================
--- dtor.orig/drivers/pci/pci-sysfs.c
+++ dtor/drivers/pci/pci-sysfs.c
@@ -293,16 +293,17 @@ pci_create_resource_files(struct pci_dev
 		if (!pci_resource_len(pdev, i))
 			continue;
 
-		res_attr = kmalloc(sizeof(*res_attr) + 10, GFP_ATOMIC);
+		/* allocate attribute structure, piggyback attribute name */
+		res_attr = kcalloc(1, sizeof(*res_attr) + 10, GFP_ATOMIC);
 		if (res_attr) {
-			memset(res_attr, 0, sizeof(*res_attr) + 10);
+			char *res_attr_name = (char *)(res_attr + 1);
+
 			pdev->res_attr[i] = res_attr;
-			/* Allocated above after the res_attr struct */
-			res_attr->attr.name = (char *)(res_attr + 1);
-			sprintf(res_attr->attr.name, "resource%d", i);
-			res_attr->size = pci_resource_len(pdev, i);
+			sprintf(res_attr_name, "resource%d", i);
+			res_attr->attr.name = res_attr_name;
 			res_attr->attr.mode = S_IRUSR | S_IWUSR;
 			res_attr->attr.owner = THIS_MODULE;
+			res_attr->size = pci_resource_len(pdev, i);
 			res_attr->mmap = pci_mmap_resource;
 			res_attr->private = &pdev->resource[i];
 			sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
Index: dtor/drivers/infiniband/core/sysfs.c
===================================================================
--- dtor.orig/drivers/infiniband/core/sysfs.c
+++ dtor/drivers/infiniband/core/sysfs.c
@@ -40,9 +40,7 @@ struct ib_port {
 	struct kobject         kobj;
 	struct ib_device      *ibdev;
 	struct attribute_group gid_group;
-	struct attribute     **gid_attr;
 	struct attribute_group pkey_group;
-	struct attribute     **pkey_attr;
 	u8                     port_num;
 };
 
@@ -60,8 +58,9 @@ struct port_attribute port_attr_##_name 
 struct port_attribute port_attr_##_name = __ATTR_RO(_name)
 
 struct port_table_attribute {
-	struct port_attribute attr;
-	int                   index;
+	struct port_attribute	attr;
+	char			name[8];
+	int			index;
 };
 
 static ssize_t port_attr_show(struct kobject *kobj,
@@ -398,17 +397,16 @@ static void ib_port_release(struct kobje
 	struct attribute *a;
 	int i;
 
-	for (i = 0; (a = p->gid_attr[i]); ++i) {
-		kfree(a->name);
+	for (i = 0; (a = p->gid_group.attrs[i]); ++i)
 		kfree(a);
-	}
 
-	for (i = 0; (a = p->pkey_attr[i]); ++i) {
-		kfree(a->name);
+	kfree(p->gid_group.attrs);
+
+	for (i = 0; (a = p->pkey_group.attrs[i]); ++i)
 		kfree(a);
-	}
 
-	kfree(p->gid_attr);
+	kfree(p->pkey_group.attrs);
+
 	kfree(p);
 }
 
@@ -449,58 +447,45 @@ static int ib_device_hotplug(struct clas
 	return 0;
 }
 
-static int alloc_group(struct attribute ***attr,
-		       ssize_t (*show)(struct ib_port *,
-				       struct port_attribute *, char *buf),
-		       int len)
+static struct attribute **
+alloc_group_attrs(ssize_t (*show)(struct ib_port *,
+				  struct port_attribute *, char *buf),
+		  int len)
 {
-	struct port_table_attribute ***tab_attr =
-		(struct port_table_attribute ***) attr;
+	struct attribute **tab_attr;
+	struct port_table_attribute *element;
 	int i;
-	int ret;
-
-	*tab_attr = kmalloc((1 + len) * sizeof *tab_attr, GFP_KERNEL);
-	if (!*tab_attr)
-		return -ENOMEM;
 
-	memset(*tab_attr, 0, (1 + len) * sizeof *tab_attr);
-
-	for (i = 0; i < len; ++i) {
-		(*tab_attr)[i] = kmalloc(sizeof *(*tab_attr)[i], GFP_KERNEL);
-		if (!(*tab_attr)[i]) {
-			ret = -ENOMEM;
-			goto err;
-		}
-		memset((*tab_attr)[i], 0, sizeof *(*tab_attr)[i]);
-		(*tab_attr)[i]->attr.attr.name = kmalloc(8, GFP_KERNEL);
-		if (!(*tab_attr)[i]->attr.attr.name) {
-			ret = -ENOMEM;
+	tab_attr = kcalloc(1 + len, sizeof(struct attribute *), GFP_KERNEL);
+	if (!tab_attr)
+		return NULL;
+
+	for (i = 0; i < len; i++) {
+		element = kcalloc(1, sizeof(struct port_table_attribute),
+				  GFP_KERNEL);
+		if (!element)
 			goto err;
-		}
 
-		if (snprintf((*tab_attr)[i]->attr.attr.name, 8, "%d", i) >= 8) {
-			ret = -ENOMEM;
+		if (snprintf(element->name, sizeof(element->name),
+			     "%d", i) >= sizeof(element->name))
 			goto err;
-		}
-
-		(*tab_attr)[i]->attr.attr.mode  = S_IRUGO;
-		(*tab_attr)[i]->attr.attr.owner = THIS_MODULE;
-		(*tab_attr)[i]->attr.show       = show;
-		(*tab_attr)[i]->index           = i;
-	}
 
-	return 0;
+		element->attr.attr.name  = element->name;
+		element->attr.attr.mode  = S_IRUGO;
+		element->attr.attr.owner = THIS_MODULE;
+		element->attr.show       = show;
+		element->index		 = i;
 
-err:
-	for (i = 0; i < len; ++i) {
-		if ((*tab_attr)[i])
-			kfree((*tab_attr)[i]->attr.attr.name);
-		kfree((*tab_attr)[i]);
+		tab_attr[i] = &element->attr.attr;
 	}
 
-	kfree(*tab_attr);
+	return tab_attr;
 
-	return ret;
+err:
+	while (--i >= 0)
+		kfree(tab_attr[i]);
+	kfree(tab_attr);
+	return NULL;
 }
 
 static int add_port(struct ib_device *device, int port_num)
@@ -541,23 +526,20 @@ static int add_port(struct ib_device *de
 	if (ret)
 		goto err_put;
 
-	ret = alloc_group(&p->gid_attr, show_port_gid, attr.gid_tbl_len);
-	if (ret)
-		goto err_remove_pma;
-
 	p->gid_group.name  = "gids";
-	p->gid_group.attrs = p->gid_attr;
+	p->gid_group.attrs = alloc_group_attrs(show_port_gid, attr.gid_tbl_len);
+	if (!p->gid_group.attrs)
+		goto err_remove_pma;
 
 	ret = sysfs_create_group(&p->kobj, &p->gid_group);
 	if (ret)
 		goto err_free_gid;
 
-	ret = alloc_group(&p->pkey_attr, show_port_pkey, attr.pkey_tbl_len);
-	if (ret)
-		goto err_remove_gid;
-
 	p->pkey_group.name  = "pkeys";
-	p->pkey_group.attrs = p->pkey_attr;
+	p->pkey_group.attrs = alloc_group_attrs(show_port_pkey,
+						attr.pkey_tbl_len);
+	if (!p->pkey_group.attrs)
+		goto err_remove_gid;
 
 	ret = sysfs_create_group(&p->kobj, &p->pkey_group);
 	if (ret)
@@ -568,23 +550,19 @@ static int add_port(struct ib_device *de
 	return 0;
 
 err_free_pkey:
-	for (i = 0; i < attr.pkey_tbl_len; ++i) {
-		kfree(p->pkey_attr[i]->name);
-		kfree(p->pkey_attr[i]);
-	}
+	for (i = 0; i < attr.pkey_tbl_len; ++i)
+		kfree(p->pkey_group.attrs[i]);
 
-	kfree(p->pkey_attr);
+	kfree(p->pkey_group.attrs);
 
 err_remove_gid:
 	sysfs_remove_group(&p->kobj, &p->gid_group);
 
 err_free_gid:
-	for (i = 0; i < attr.gid_tbl_len; ++i) {
-		kfree(p->gid_attr[i]->name);
-		kfree(p->gid_attr[i]);
-	}
+	for (i = 0; i < attr.gid_tbl_len; ++i)
+		kfree(p->gid_group.attrs[i]);
 
-	kfree(p->gid_attr);
+	kfree(p->gid_group.attrs);
 
 err_remove_pma:
 	sysfs_remove_group(&p->kobj, &pma_group);